Remote controls have become invaluable tools for controlling devices. Remote controls use ElectroMagnetic (EM) signals, such as Radio Frequency (RF) or infrared (IR) signals, to represent and communicate remote control codes from the remote control to a device. In typical remote controls, buttons are assigned function codes. When a button is pressed, an infrared (IR) remote control, for example, uses the function code when determining a corresponding remote control code and creates an IR signal corresponding to the remote control code.
The IR signal is generated at a particular carrier frequency and generally comprises a header, a device code, the function code corresponding to the button, and a trailer. The header is used to alert a device that a remote control signal is being sent. The device code is used to distinguish between devices using the same carrier frequency. For example, a manufacturer might make remote controls for two devices. Each remote control for the two devices could use the same carrier frequency for IR signals, but each device will be assigned a different device code. When a device receives an IR signal, the device determines whether the device code is the device code assigned to the device. If so, the device will interpret the function code and perform the function corresponding to the function code. If not, the device will ignore the function code. The trailer is used to alert the device that the IR signal is ending.
Each manufacturer has the ability to specifically design remote control codes and their corresponding EM signals to meet its own requirements. For example, sometimes the EM signal includes a “repeat portion,” which can include, for instance, the device code and the function code or simply the function code. The repeat portion is repeated for a certain number of times or while the button is pressed. The repeat portion helps to ensure that the function code is received by the device and can also be used to cause the function code to be performed multiple times.
Systems using typical IR or RF remote controls and corresponding devices tend to be very robust. Quite a bit of error, as much as ten percent or more, can occur in an IR signal, for instance, yet the correct function corresponding to the IR signal will still be performed.
Although remote controls and systems using the same are robust and beneficial, a number of significant problems remain. For instance, there can be times when signals from one remote, chosen to operate a first device, will inadvertently operate an unintended, second device. This is particularly true when the remote control and device use RF to communicate with each other, although systems using IR for communication also can be subject to such inadvertent operations. Consequently, what is needed are techniques for solving these problems.